-E-

Elasticity . . . The property of recovering original shape and dimensions upon removal of a deforming force.

Elastic Limit . . . Maximum stress that a material will withstand without permanent deformation. See Yield Strength.

Electrical Precipitator . . . In air pollution control, the use of electrodes in stack emissions emitting high voltage; particles 0.1 micron and smaller can be attached and collected at discharge electrode.

Electrochemical Corrosion (Contact Corrosion, Electrolytic Corrosion, Galvanic Corrosion) . . . Localized corrosion from,exposure of an assembly of dissimilar metals in contact or coupled with one another, i.e., electrochemical action.

Electrode . . . Compressed graphite or carbon cylinder or rod used to conduct electric current in electric arc furnaces, arc lamps, carbon arc welding, etc.

Electron Microprobe Analyzer . . . An instrument for selective analysis of a microscopic area, in which an electron beam bombards the point of interest in Vacuo at a given energy level. Intensity of backscatter is measured to interpret which chemical elements are present and by scanning a large area the microprobe can analyze chemical composition and indicate the distribution of an element.

Elongation . . . Amount of permanent extension in the vicinity of the fractures in the tensile test; usually expressed as a percentage of original gage length, such as 25 percent in 2 in.

Embrittlement . . . Loss of ductility. See Acid Embrittlement, Hydrogen Embrittlement.

Endothermic Reaction . . . Designating, or pertaining to a reaction which occurs with absorption of heat from the surroundings; as an endothermic substance.

Equilibrium ... A dynamic condition of balance between atomic movements, where the resultant is zero and the condition appears to be one of rest rather than change.

Erosion ... Abrasion of metal or other material by liquid or gas, usually accelerated by pressure of solid particles of matter in suspension, and sometimes by corrosion.

Etchant ... A solution for chemical etching the polished surface of a metal specimen to reveal macro- or microstructures when viewed under microscope.

Exothermic . . . Formed by or characterized by heat reaction, as in oxidation.

Exothermic Reaction . . . Chemical reactions involving the liberation of heat; such as burning of fuel, deoxidizing of iron with aluminum, and a characteristic of many feeder or riser compounds. See Endothermic Reaction.

Extensometer . . . An instrument used in the testing of metals to measure small increments of deformation.